1. Field of the Invention
The present invention relates to a die clamping apparatus with an ejecting mechanism for separating molded articles from a die assembly, which may be used for a die-casting machine or a plastic injection molding machine.
2. Description of the Related Art
In an injection molding machine for molding a resin material such as a plastic material, a die clamping apparatus for a die assembly is provided, which die clamping apparatus is provided with an ejector or pushing-out mechanism for detaching a molded article from the die assembly. The die clamping apparatus is for closing and opening a die assembly. At the closed condition by the die clamping apparatus, the die assembly is subjected to a clamping operation at a desired clamping force in the die assembly. The ejector mechanism in the die clamping apparatus is provided with ejector pins, which are selectively projected into a cavity formed by the die assembly. Namely, when the die assembly is opened as the result of a completion of a molding process, the ejector pins are projected into the cavity, thereby causing a finished product to be removed.
In a prior art construction, an ejector pin of an ejecting mechanism and the die are separately operated by different actuators. Thus, the prior art construction is defective in that a construction is complicated and a cost is increased.
An object of the present invention is to provide a die apparatus capable of overcoming difficulties in the prior art.
Another object of the present invention is to provide a die apparatus capable of obtaining a positive operation of a pushing-out operation in relation to the opening/closing operation of the die clamping apparatus.
According to a first aspect of the invention, a die apparatus is provided, comprising: a stationary die; a stationary die plate on which the stationary die is held; a moving die; a moving die plate on which the moving die is held while the moving die being faced with the stationary die; die clamping means for selectively opening and closing the dies as well as for clamping the dies; at least one pushing-out pin selectively projected from and retracted to the moving die; a movable member connected to the pushing-out pin and arranged movably with respect to the moving die plate, and; means for constraining the movement of the movable member in the die opening and closing directions when the movable member is moved to a predetermined die opening position, such that, with respect to the moving die plate moved further in the die opening direction from the predetermined die opening position or moved in the die closing direction toward the die opening position, only the movement of the movable plate is constrained by the constraining means.
In the operation of the first aspect of the invention, the movement of the movable member connected to the pushing-out pin in the die opening direction is constrained by the constraining means when the moving die plate is moved to the die opening position. A further movement of the moving die plate in the die opening direction from the die opening position allows only the movement of the moving die plate, while the movable member to be kept stopped. As a result, a relative movement is obtained between the movable member and the moving die plate, which cause the pushing-out pin to be projected from the moving die, which causes a product to be separated.
After the completion of the ejection of the product, the moving die plate is returned to the die opening position in the die closing direction. During the movement, the movable member is also constrained by the constraining means. As a result, the pushing-out pin connected to the movable member is retracted to the die surface of the moving die. Namely, in the present invention, a retraction of the pushing-out pin to the moving die is not done by a spring force as is the case in the prior art but is done by the movement of the moving die itself. Thus, a reliable retraction of the pushing-out pin to a predetermined position can be obtained even in a situation where a desired function of a return spring is lost under a reason that molten metal is attached and solidified to the coil spring.
According to a second aspect of the present invention, a die apparatus is provided, which comprises: a stationary die; a stationary die plate on which the stationary die is held; a moving die; a moving die plate on which the moving die is held while the moving die being faced with the stationary die; die clamping means for selectively opening and closing the dies as well as for clamping the dies; at least one pushing-out pin selectively projected from and retracted to the moving die; a movable member connected to the pushing-out pin and arranged movably with respect to the moving die plate; means for constraining the movement of the movable member in the die opening and closing directions when the movable member is moved to a predetermined die opening position, such that, with respect to the moving die plate moved further in the die opening direction from the predetermined die opening position, only the movement of the movable plate is constrained by the constraining means, thereby generating a resultant relative movement between the movable member and the moving die plate, so that the pushing-out pin is projected from the moving die, which causes a molded product to be pushed out, and; means for preventing the moving die plate from being moved at least in the forward direction from the die opening position after the completion of the pushing-out operation for a separation of a molded product so long as the constraining operation by the constraining means is maintained.
In this second aspect of the invention, the die clamping means comprise a link housing and drive means arranged between the link housing and the moving die plate for generating a die clamping force, and wherein the constraining means constrains the movable member with respect to the to the link housing.
In the second aspect of the invention, the constraining means comprise an actuator mounted on one of the link housing and the moving die plate for causing the link housing and the moving die plate to be engaged with each other.
In the operation of the second aspect of the invention, the movement of the movable member connected to the pushing-out pin in the die opening direction is constrained by the constraining means when the moving die plate is moved to the die opening position. A further movement of the moving die plate in the die opening direction from the die opening position allows only the movement of the moving die plate, while the movable member to be kept stopped. As a result, a relative movement is obtained between the movable member and the moving die plate, which cause the pushing-out pin to be projected from the moving die, which causes a product to be separated from the moving die.
When the moving die plate is in the die opening position, the movable member is constrained by the constraining means and the moving die plate is prevented from being moved with respect to the movable member from the home position in the die closing direction, so that the moving die plate is prevented from being moved from the die closing direction from the die opening direction so long as the constraining means is operated. Thus, the present invention can function as a safety mechanism which prevents the die apparatus from being accidentally closed.
According to a third aspect of the present invention, a die apparatus is provided, which comprises: a stationary die; a stationary die plate on which the stationary die is held; a moving die; a moving die plate on which the moving die is held while the moving die being faced with the stationary die; die clamping means for selectively opening and closing the dies as well as for clamping the dies; at least one pushing-out pin selectively projected from and retracted to the moving die; a movable member connected to the pushing-out pin and arranged movably with respect to the moving die plate; urging means for urging the movable member with respect to the moving die plate movable so that a position is obtained, where the pushing-out pin is held in positions retracted into the moving die plate, and; means for constraining the movement of the movable member in the die opening and closing directions when the movable member is moved to a predetermined die opening position, such that, with respect to the moving die plate moved further in the die opening direction from the predetermined die opening position, only the movement of the movable plate is constrained by the constraining means, so that a resultant relative movement between the movable member and the moving die plate causes the pushing-out pin to be projected from the moving die, which causes a molded product to be pushed out, while the constraint of the movable member being kept until the moving die plate is returned to the die opening position.
In the third aspect of the invention, the preventing means comprise stoppers arranged between the movable member and the moving die plate for preventing a relative movement of the die plate with respect to the movable plate in die closing direction from a prefixed relative position between the movable member and the moving die plate, whereby under the constraining operation of the constraining means, the movement of the moving die plate in the die closing direction is prevented.
In the third aspect of the invention, the die clamping means comprise a link housing and drive means arranged between the link housing and the moving die plate for generating a die clamping force.
In the third aspect of the invention, a die apparatus further comprises means for preventing the moving die plate from being moved at least in the forward direction from the die opening position so long as the constraining means is not released.
In the third aspect of the invention, the constraining means comprise an engaging member mounted on one of the link housing and the moving die plate, and actuating means for causing the engaging member to be selectively engaged with the other of the link housing and the moving die plate.
In the die apparatus in the third aspect of the invention, the movable member connected to the pushing-out pin is constrained in its movement in the die opening and closing directions by the constraining means when the moving die plate is moved to the predetermined die opening condition. When a further movement of the moving die plate in the die opening direction from the die opening position is obtained, only the moving die plate is moved, while the movable member is kept stopped. As a result, a relative movement is obtained between the movable member and the moving die plate, which causes the pushing-out pin to be projected from the moving die, resulting in a detachment of the obtained product.
Upon the completion of the pushing-out operation of the molded product, the constraining operation of the movable member is kept until the moving die plate is returned to the predetermined die opening position. Thus, upon the completion of the return to the predetermined die opening position, a positive return of the movable member to the home position with respect to the moving die plate is obtained. Thus, at the returned condition of the moving die plate to the die opening position, the pushing-out pin is positively prevented from being projected from the moving die.
According to the fourth aspect of the invention, a die apparatus is provided, comprising: a stationary die; a stationary die plate on which the stationary die is held; a moving die; a moving die plate on which the moving die is held while the moving die being faced with the stationary die; die clamping means for selectively opening and closing the dies as well as for clamping the dies; at least one pushing-out pin selectively projected from and retracted to the moving die; a movable member connected to the pushing-out pin and arranged movably with respect to the moving die plate; first constraining means for preventing the movable member from being moved from a home position with respect to the moving die plate; second constraining means for preventing the movable member from being moved in the die opening and closing directions when a when the movable member is moved to a predetermined die opening position; the arrangement of the first and second constraining means being such that, with respect to the moving die plate moved further in the die opening direction from the predetermined die opening position, only the movement of the movable plate is constrained by the second constraining means, so that a resultant relative movement between the movable member and the moving die plate causes the pushing-out pin to be projected from the moving die, which causes a molded product to be pushed out and such that, except for a condition where the relative movement is to be obtained, the movable member is always constrained the first constraining means.
In the third aspect of the invention, the die clamping means comprise a link housing and drive means arranged between the link housing and the moving die plate for generating a die clamping force, and wherein the second constraining means constrains the movable member with respect to the link housing.
In this fourth aspect of the invention, a die apparatus further comprises means for preventing the moving die plate from being moved in the forward direction from the die opening position so long as the constraining operation by the second constraining means is not released.
In the fourth aspect of the invention, the first and second constraining means are integrated such that a selective operation is obtained between the constraint of the movable member from the home position with respect to the moving die plate and the constraint of the movable member to the die opening and closing direction after the movement to the predetermined die opening position is obtained.
In the fourth aspect of the invention, the first constraining means are arranged on one of the moving die plate and the movable member and having an actuator for causing the moving die plate and the movable member to be engaged with each other, and wherein the second constraining means are arranged on one of the link housing and the moving die plate, and having an actuator for causing the link housing and the moving die plate to be engaged with each other.
In the operation of the fourth aspect of the invention, the movable member connected to the pushing-out pin is constrained by the first constraining means until the moving die plate is moved to the predetermined die opening position. Thus, a home position of the movable member with respect to the moving die plate is reliably obtained. When the movable member is moved to the predetermined die opening position, a constraint by the second constraining means is obtained in the die opening and closing directions. Prior to the commencement of the relative movement between the movable member and the moving die plate, a constraint by the first constraining means is released, which allows a relative movement between the movable member and the moving die plate, which causes the pushing-out pin to be projected from the moving die, resulting in a separation of the molded product the moving die.
When the return of the moving die plate to the predetermined die opening position is completed after the completion of the pushing-out operation of the molded product, the movable member is positively returned to a home position with respect to the moving die plate. Thus, the movable member is prevented from being moved from the home position, thereby preventing the die clamping operation from being executed under the projected condition of the pushing-out pin from the moving die.